﻿30 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  6T 
  

  

  CAMPTOCRINUS 
  CRAWFORDSVILLENSIS, 
  new 
  species 
  

  

  Plate 
  8, 
  figs. 
  1-3 
  e 
  

  

  Camptocrinus 
  myclodactylus 
  Wachsmtjth 
  and 
  Springer, 
  North 
  Amcr. 
  

   Crin. 
  Cam., 
  1897, 
  pi. 
  75, 
  fig. 
  1 
  (not 
  2a, 
  b). 
  

  

  Coil 
  open, 
  not 
  closely 
  enveloping 
  the 
  crown. 
  Cirri 
  doubled, 
  or 
  

   rarely 
  trebled, 
  as 
  in 
  the 
  preceding 
  species, 
  or 
  exceptionally 
  single, 
  

   and 
  springing 
  from 
  a 
  pair 
  of 
  short 
  nodal 
  columnals; 
  but 
  instead 
  of 
  

   these 
  alternating 
  with 
  a 
  single 
  longer 
  one, 
  there 
  are 
  2, 
  3, 
  or 
  excep- 
  

   tionally 
  4 
  internodals 
  interposed 
  between 
  them, 
  each 
  about 
  the 
  size 
  

   of 
  the 
  combined 
  pair. 
  The 
  marginal 
  cirri 
  on 
  either 
  side 
  are 
  long 
  

   and 
  fairly 
  stout, 
  composed 
  of 
  20 
  to 
  25 
  cirrals; 
  and 
  in 
  addition 
  to 
  

   them 
  there 
  are, 
  especially 
  toward 
  the 
  distal 
  end, 
  remnants 
  of 
  smaller 
  

   secondary 
  cirri 
  at 
  the 
  back 
  of 
  the 
  same 
  columnals, 
  as 
  if 
  forming 
  

   rudimentary 
  whorls; 
  where 
  these 
  appear 
  the 
  stem 
  tends 
  to 
  lose 
  its 
  

   bilateral 
  form 
  and 
  become 
  round. 
  This 
  structure, 
  occurring 
  in 
  a 
  

   different 
  horizon 
  of 
  the 
  Keokuk 
  from 
  that 
  of 
  the 
  last 
  species, 
  is 
  

   constant 
  in 
  three 
  specimens. 
  The 
  stem 
  is 
  not 
  preserved 
  to 
  its 
  full 
  

   length 
  in 
  an}' 
  of 
  them, 
  but 
  extends 
  well 
  beyond 
  the 
  proximal 
  coil. 
  

   The 
  calyx 
  is 
  that 
  of 
  the 
  typical 
  Dichocrinus, 
  elongate 
  with 
  base 
  one 
  

   third 
  the 
  height 
  of 
  the 
  cup. 
  Arms 
  two 
  to 
  the 
  ray, 
  composed 
  of 
  

   rather 
  long, 
  quadrangular 
  ossicles. 
  The 
  crown 
  is 
  relatively 
  larger 
  

   than 
  in 
  the 
  succeeding 
  species. 
  

  

  Horizon 
  and 
  localthj. 
  — 
  Mississippian, 
  Keokuk 
  limestone, 
  upper 
  

   horizon; 
  Crawfordsville, 
  Montgomery 
  County, 
  Indiana. 
  

  

  CAMPTOCRINUS 
  PLENICIRRUS, 
  new 
  species 
  

  

  Plate 
  7, 
  figs. 
  6, 
  G« 
  

  

  This 
  species 
  is 
  proposed 
  for 
  a 
  small 
  specimen 
  associated 
  with 
  the 
  

   preceding 
  which, 
  while 
  of 
  the 
  typical 
  Camptocrinus 
  type 
  in 
  the 
  

   curvature, 
  form 
  and 
  proportions 
  of 
  the 
  stem 
  and 
  its 
  elliptic 
  section, 
  

   has 
  the 
  cirri 
  developed 
  into 
  complete 
  whorls 
  of 
  five, 
  nearly 
  equal 
  in 
  

   size. 
  In 
  the 
  arrangement 
  of 
  columnals, 
  with 
  paired 
  short 
  nodals 
  

   and 
  a 
  single 
  long 
  internodal, 
  it 
  is 
  like 
  C. 
  myelodactylus, 
  but 
  the 
  cirri 
  

   are 
  distributed 
  on 
  a 
  different 
  plan; 
  also 
  it 
  comes 
  from 
  a 
  different 
  

   horizon. 
  From 
  the 
  other 
  Crawfordsville 
  species, 
  last 
  described, 
  it 
  

   differs 
  in 
  the 
  single 
  internodal, 
  instead 
  of 
  two 
  or 
  more, 
  and 
  in 
  the 
  

   short, 
  strongly 
  tapering 
  cirri 
  not 
  arranged 
  in 
  marginal 
  rows. 
  Un- 
  

   fortunately 
  less 
  than 
  half 
  the 
  stem 
  is 
  preserved 
  ; 
  if 
  we 
  had 
  the 
  whole 
  

   of 
  it, 
  I 
  have 
  no 
  doubt 
  we 
  should 
  find 
  it 
  circular 
  toward 
  the 
  distal 
  

   end. 
  The 
  species 
  represents 
  a 
  stage 
  in 
  the 
  modifications 
  of 
  the 
  type 
  

   under 
  consideration 
  in 
  which 
  the 
  cirri 
  have 
  resumed 
  almost 
  the 
  

   distribution 
  of 
  those 
  in 
  a 
  normal 
  crinoid. 
  

  

  